A good real estate agent will ask you to fill out a simple form to determine your debt ratios and get your credit score (if you do not already have it). This is simply good business practice for real estate agents, since no agent wants to waste time showing you homes that you will not be able to afford to buy.
However, the agent will most likely show you the highest-priced homes for which you can qualify. This is also good business, since you are more likely to fall in love with a higher-priced home than a less expensive one. Once you fall in love, it is an easy sale. Remember, once you look at the most you can possibly afford, less expensive homes will be disappointing. Always try to look at the least expensive homes first and work your way up until you find one that satisfies both your needs and desires.